Separation and Quantification of Superwarfarin Rodenticide Diastereomers-Bromadiolone, Difenacoum, Flocoumafen, Brodifacoum, and Difethialone-in Human Plasma.

Abstract

Superwarfarins, second-generation long-acting anticoagulant rodenticides, are 4-hydroxycoumarin analogues of warfarin that contain a large hydrophobic side chain. These compounds contain two chiral centers and are synthesized for commercial use as two pairs of diastereomer. To support studies of superwarfarin pharmacokinetics and other efforts to improve clinical care for poisoning victims, a quantitative assay was developed for the measurement of diastereomer of bromadiolone, difenacoum, flocoumafen, brodifacoum, and difethialone in human plasma. Based on ultrahigh-pressure liquid chromatography-tandem mass-spectrometry (UHPLC-MS/MS), this method was validated according to U.S. Food and Drug Administration (FDA) guidelines. Sample preparation involved simple protein precipitation followed by reversed phase UHPLC, which resolved all five pairs of cis/trans diastereomer in less than 10 min. Superwarfarins were measured using negative ion electrospray followed by selected-reaction monitoring on a triple quadrupole mass spectrometer. Calibration curves covered 3-4 orders of magnitude with linear regression coefficients of >0.999. The lower limits of quantitation were from 0.013 to 2.41 ng/mL, and intra-day and inter-day accuracy and precision coefficients of variation were <12%. A 10-min UHPLC-MS/MS assay was developed and validated for the separation and quantitative analysis of the pairs of diastereomer of five superwarfarins in human plasma. This method was used to identify and measure superwarfarins and their cis/trans diastereomers in plasma obtained from patients treated for coagulopathy following consumption of contaminated synthetic cannabinoid products.